The present invention relates to a compound containing polyfluoroalkoxides and the use thereof, in particular, for use as an electrolyte in batteries and other electrochemical devices.
A compound containing a weakly coordinating anion (i.e., an anion that coordinates only weakly with a cation) is useful in a variety of applications including as an electrolyte and a counter-ion for a catalyst in a variety of organic reactions. Some of the useful catalysts containing a weakly coordinating anion are described by Barbarich, et al. in xe2x80x9cLiAl(OC(Ph)(CF3)2)4: A Hydrocarbon-Soluble Catalyst For Carbon-Carbon Bond-Forming Reactionsxe2x80x9d, Organometallics, 1996, 15, 3776, which is incorporated herein in its entirety.
Investigations of very reactive metal and nonmetal cations continues to spur the development of new weakly coordinating anions. See, for example, Bochmann, Angew. Chem., Int. Ed. Engl. 1992, 31 1181; Strauss, Chem. Rev. 1993, 93, 927, Strauss, Chemtracts-Inorganic Chem. 1994, 6,1; and Seppelt, Angew. Chem., Int. Ed. Engl. 1993, 32, 1025. One of the most important uses of weakly coordinating anions is to enhance the catalytic activity of metal cations. Two examples that have received considerable attention recently are metallocene-catalyzed olefin polymerization, and lithium-catalyzed Diels-Alder reactions and 1,4-conjugate addition reactions. See Turner, European Patent Appl. No. 277,004, 1988; Pellecchia et al., Makromol. Chem., Rapid Commun. 1992, 13, 265; DuBay et al., J. Org. Chem. 1994, 59, 6898; Saidi et al., Chem. Ber. 1994, 127, 1761; Kobayashi et al., Chem. Lett. 1995, 307; and Arai et al., Angew. Chem., Int. Ed. Engl. 1996, 15, 3776.
Useful anions must not only be weakly coordinating, they must also be stable with respect to oxidation and/or fragmentation in the presence of highly electrophilic cations. In addition, an ideal weakly coordinating anion should have a single negative charge dispersed over a large surface composed of relatively nonpolar bonds to weakly basic atoms such as hydrogen or the halogens. Weakly coordinating anions which conform to many, but not all, of these criteria include B (Arf)4xe2x88x92 (Arf=C6F5 or 3,5-C6H3(CF3)2), CB11H12-nXnxe2x88x92 (X=H, Me, Cl, Br, F or I), CB9H10-nXnxe2x88x92 (X=H, F, Cl, or Br), and M(OTeF5)nxe2x88x92 (n=4, M=B; n=6, M=Nb, Sb).
All of the anions mentioned above have limitations. Some are too strongly coordinating for specific applications. Some are unstable under the harsh chemical conditions where they would be employed. For example, the fluorinated derivatives of BPh4xe2x88x92 can react with strongly electrophilic cations, causing (i) cleavage of a Cxe2x80x94F bond and formation of a bond between the fluorine atom and the cation or (ii) transfer of a fluoroaryl group to the cation. In either case, the cation is no longer reactive or catalytically active.
Other weakly coordinating anions, such as ClO4xe2x88x92, BF4xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92, B(OTeF5)4xe2x88x92, and Nb(OTeF5)6xe2x88x92, are not thermally and/or hydrolytically stable. In addition, lithium salts of such anions, including LiCF3SO3, have low electrical conductivity in some organic solvents, especially organic solvents that are stable in the presence of strong reducing agents such as metallic lithium and related lithium-containing battery anode solutions. Furthermore, some lithium salts, such as lithium triflate (LiCF3SO3), cause corrosion of the aluminum current collectors in batteries, while some lithium salts, such as LiPF6, are known to be unstable at temperatures as low as 70xc2x0 C. and decompose over time.
Still other anions containing boron atoms, and anions containing a carbon atom and a cluster of boron atoms, such as carboranes (e.g., CB5, CB9, CB11), are not particularly weakly coordinating because the salts formed therefrom contain at most only one fluorine atom which is bonded to a boron atom.
Recently, polyfluorinated carborane anions that are weakly coordinating and are thermally and/or hydrolytically stable have been disclosed in commonly assigned U.S. patent application Ser. No. 09/049,420, filed Mar. 27, 1998. In addition, one particular class of compounds containing polyfluoroalkoxide ligands and the use thereof has been disclosed in commonly assigned PCT Patent Application No. PCT/US98/19268, filed Sep. 11, 1998, and commonly assigned U.S. patent application Ser. No. 09/151,852, filed Sep. 11, 1998, disclosures of which are incorporated herein by reference in their entirety.
Despite the recent advances in weakly coordinating anions, there still is a need for new weakly coordinating anions. There is also a need for weakly coordinating anions having a high electrical conductivity in an organic solvent. There is also a need for weakly coordinating anions that are stable in solution and in the solid state.
One embodiment of the present invention provides a compound comprising a monoanion of the formula: 
and uses thereof,
where
M1 is a transition metal, or a Group III, IV or V element;
each Z is independently O, S, or NR6R7;
each X is independently a halide;
each R1 is independently a bond or C1-C4 alkylene;
each of R2, R3and R4 is independently H, F, fluorinated C1-C10 alkyl, fluorinated C4-C20 aryl, C3-C10 cycloalkyl, fluorinated C3-C10 cycloalkyl, C1-C10 alkyl or C4-C20aryl, provided at least one of R2, R3 and R4 is F, fluorinated C1-C10 alkyl, fluorinated C3-C10 cycloalkyl, or fluorinated C4-C20 aryl;
each R5 is independently fluorinated C1-C10 alkyl, fluorinated C4-C20 aryl, C4-C20 aryloxide, fluorinated C4-C20 aryloxide, C1-C10 alkoxide or fluorinated C1-C10 alkoxide;
each of R6 and R7 is independently H or C1-C10 alkyl;
each of a, b and c is independently an integer from 0 to 4,
provided the sum of a, b and c is an integer from 2 to 8; and n is 1 or 2; and
provided that when R2 is a fluorinated C1 -C4 alkyl, R1 is a bond, b, and c are 0, and R3 is C1-C10 alkyl or fluorinated C4-C10 alkyl then R4 is F, fluorinated C1-C10 alkyl or fluorinated C4-C20 aryl.
Another embodiment of the present invention provides a compound comprising an anion of the formula: 
wherein
M1 is a transition metal, or a Group III, IV or V element;
L is a halide, C1-C10 alkyl, fluorinated C1-C10 alkyl, C4-C20 aryl, fluorinated C1-C20 alkyl or a moiety of the formula xe2x88x92Z3-R11;
d is an integer from 0 to 4;
e is an integer from 1 to 3;
the sum of d and e is an integer from 1 to 6;
n is 1 or 2;
each of Z1, Z2 and Z3 is independently O, S, or NR6R7;
each of R6 and R7 is independently H or C1-C10 alkyl;
each R9 is independently C1-C30 alkylene, fluorinated C1-C30 alkylene, substituted C1-C30 alkylene, C3-C10 cycloalkylene, fluorinated C3-C10 cycloalkylene, C4-C20 arylene or fluorinated C4-C20 arylene;
each of R8 and R10 is a bond, or a moiety of the formula xe2x80x94[C(R12R13)]xxe2x80x94;
each x is independently an integer from 1 to 4;
each of R12 and R13 is independently H, F, C1-C4 alkyl or fluorinated C1-C4 alkyl; and
each R11 is independently C1-C10 alkyl, fluorinated C1 -C10 alkyl, C4-C20 aryl, or fluorinated C4-C20 aryl;
provided at least one of R8 and R10 is a moiety of the formula xe2x80x94C(R12R13)xe2x80x94 and at least one of R12 and R13 is F or fluorinated C1-C4 alkyl.
The present invention also provides an electrolyte for an electrochemical device, comprising the anion of the above described formula having a counter cation M where M is a metal cation, a phosphonium cation, an ammonium cation or a sulfonium cation. Preferably M is Li cation.
The present invention provides a compound comprising an anion of the formula: 
and uses thereof, where M1 is a transition metal, or a Group III, IV or V element, preferably M1 excludes Cu; each Z is independently O, S, or NR6R7; each X is independently a halide; each R1 is independently a bond or C1-C4 alkylene; each of R2, R3 and R4 is independently H, F, fluorinated C1-C10 alkyl, fluorinated C4-C20 aryl, C3-C10 cycloalkyl, fluorinated C3-C10 cycloalkyl, C1-C10 alkyl or C4-C20 aryl, provided at least one of R2, R3 and R4 is F, fluorinated C1-C10 alkyl, fluorinated C3-C10 cycloalkyl, or fluorinated C4-C20 aryl; each R5 is independently fluorinated C1-C10 alkyl, fluorinated C4-C20 aryl, C4-C20 aryloxide, fluorinated C4-C20 aryloxide, C1-C10 alkoxide or fluorinated C1-C10 alkoxide; each of R6 and R7 is independently H or C1-C10 alkyl; each of a, b and c is independently an integer from 0 to 4, provided the sum of a, b and c is an integer from 2 to 8; and n is 1 or 2; provided that when R2 is a fluorinated C1-C4 alkyl, R1 is a bond, b, and c are 0, and R3 is C1-C10 alkyl or fluorinated C1-C10 alkyl then R4 is F, fluorinated C1-C10 alkyl or fluorinated C4-C20 aryl.
The present invention also provides a compound comprising an anion of the formula: 
where M1 is a transition metal, or a Group III, IV or V element; L is a halide, C1-C10 alkyl, fluorinated C1-C10 alkyl, C4-C20 aryl, fluorinated C4-C20 alkyl or a moiety of the formula xe2x80x94Z3xe2x80x94R11; d is an integer from 0 to 4; e is an integer from 1 to 3; the sum of d and e is an integer from 1 to 6; n is 1 or 2; each of Z1, Z2 and Z3 is independently O, S, or NR6R7; each of R6 and R7 is independently H or C1-C10 alkyl; each R9 is independently C1-C30 alkylene, fluorinated C1-C30 alkylene, substituted C1-C30 alkylene, C3-C10 cycloalkylene, fluorinated C3-C10 cycloalkylene, C4-C20 arylene or fluorinated C4-C20 arylene; each of R8 and R10 is a bond, or a moiety of the formula xe2x80x94[C(R12R13)]xxe2x80x94; each x is independently an integer from 1 to 4; each of R12 and R13 is independently H, F, C1-C4 alkyl or fluorinated C1-C4 alkyl; and each R11 is independently C1-C10 alkyl, fluorinated C1-C10 alkyl, C4-C20 aryl, or fluorinated C4-C20 aryl; provided at least one of R8 and R10 is a moiety of the formula xe2x80x94C(R12R13)xe2x80x94 and at least one of R12 and R13 is F or fluorinated C1-C4 alkyl.
Preferably, the compound of the present invention has at least two polyfluorinated alkoxide groups bonded to M1. As used herein, a xe2x80x9cpolyfluorinated anionxe2x80x9d refers to an anion of the above described formula.
The polyfluorinated anions of the present invention themselves do not necessarily comprise chemical compounds. Indeed, in an isolable compound, anions must be paired with cations to maintain electroneutrality. Thus, compounds of the present invention are, more accurately, of the formulas: 
where M is a cation having a valence of from 1 to 4. M can be any cation including a cation derived from an alkali metal; alkaline-earth metal; transition metal such as Ag, Zn, Cu, Co, Fe, Mn, Cr, V, Ti, Zr, Rh, Pd, Cd, Hg, Os, Pt, Y, Nb, Sc, Ta, Hf, and Mo; lanthanide and actinide series metal; ammonium moieties such as ammonium, tetrahydrocarbyl ammonium, e.g., tetrabutyl ammonium and tetraethyl ammonium, trihydrocarbyl ammonium, e.g., triethyl ammonium, diisopropyl ethyl ammonium and trimethyl ammonium, dihydrocarbyl ammonium, nitrogen heteroaromatic cation such as 2,6-lutidinium, methyl 2,6-lutidinium, methyl pyridinium and pyridinium, and imminium cation; phosphonium moieties including tetraalkylphosphonium, tetraaryl phosphonium and phosphonium ions containing a mixture of alkyl and aryl groups; sulfonium moieties such as sulfonium ions containing alkyl, aryl or mixtures thereof; and other suitable cations such as thallium. Furthermore, M can be a relatively stable carbocation such as a trityl moiety and related carbocations (e.g., R3C+); and other known cations such as hydronium (H3O+), H5O2+, (Et2O)nH+, H9O4+, and formylium (HCO+). Preferably, the cation (i.e., M) is selected from the group consisting of thallium, alkali metal and alkaline earth metal cations, ammonium, monohydrocarbyl ammonium, dihydrocarbyl ammonium, trihydrocarbyl ammonium, tetrahydrocarbyl ammonium, nitrogen heteroaromatic cation, tetrahydrocarbyl phosphonium, hydronium, formylium, and trityl and related carbocations; more preferably from the group consisting of trityl and related carbocations, thallium, tetrahydrocarbyl ammonium, alkali metal cations, and nitrogen heteroaromatic cation; and most preferably from the group consisting of trityl, Li+, Tl+, 2,6-lutidinium, tetraethylammonium, sodium, potassium, and N-methyl-2,6-lutidinium. As used in this invention, a xe2x80x9chydrocarbylxe2x80x9d refers to a compound having at least one carbon atom. Such compounds include aryl, alkyl, alkenyl and alkynyl. Moreover, hydrocarbyl can be straight chain, branched, or cyclic. Hydrocarbyl can also be substituted with other non hydrogen or carbon atoms such as halide, oxygen, sulfur, nitrogen or phosphorus.
It will be appreciated that a molar ratio of a cation to a polyfluorinated anion of the present invention depends on the valence of the cation. This is reflected in the values p and k, for example, if both the cation and the anion are monovalent, then k and p are 1, and there will be a 1:1 molar ratio between the cation and the polyfluorinated anion of the present invention. Whereas if the cation is divalent and the anion is monovalent, then k is 2 and p is 1, and there will be a 1:2 molar ratio between the cation and the polyfluorinated anion of the present invention. Preferably, k is an integer from 1 to 4, more preferably 1 to 3, still more preferably k is 1 or 2, and most preferably 1. Preferably p is 1 or 2 and more preferably 1.
It should be appreciated that because the polyfluorinated anions of the present invention are weakly associating (i.e., coordinating) anions, a cation associated with a polyfluorinated anion can be readily exchanged with another cation by any of the known methods including ion exchange chromatography and other ion exchange methods.
As used in this invention, Group III, IV and V elements are those elements which are listed in the Group III, IV and V of the periodic table, respectively. For example, Group III elements are B, Al, Ga, In and Tl; Group IV elements are C, Si, Ge, Sn, and Pb; and Group V elements are N, P, As, Sb and Bi.
With reference to formulas I-IV described herein:
Preferably M1 is selected from the group consisting of Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf and Sb, more preferably from the group consisting of Al, B, V, Ti, Si, Zr, Ge, Sn, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf and Sb, still more preferably from the group consisting of Al, B, Nb and Ta, and most preferably from the group consisting of Al and B.
Preferably, Z, Z1, Z2 and Z3 are O.
Preferably n is 1.
Preferably a is 1, 3 or 4, more preferably 4.
Preferably b is 0 or 1.
Preferably c is 0 or 3.
Preferably the sum of a, b and c is an integer from 2 to 8, more preferably an integer from 4 to 8, still more preferably an integer from 4 to 6, and most preferably 4.
Preferably X is fluoride.
Preferably R5 is fluorinated C4-C20 aryl or fluorinated C4-C20 aryloxide, more preferably fluorinated phenyl or phenoxide, and most preferably 2-trifluoromethylphenoxide, 3-trifluoromethylphenoxide, 4-trifluoromethylphenoxide, pentafluorophenoxide, or pentafluorophenyl.
Preferably R1 is a bond or methylene.
Preferably each of R2, R3 and R4 is independently H, F, fluorinated C1-C4 alkyl, C4-C20 aryl or fluorinated C4-C20 aryl. More preferably each of R2, R3 and R4 is independently H, F, trifluoromethyl, phenyl, 4-methylphenyl, methyl, n-butyl, 4-tert-butylphenyl, 3,5,-di(trifluoromethyl)phenyl, 3,5,-dimethylphenyl, 2,4,6-tri(trifluoromethyl)phenyl, 4-(triisopropylsilyl)-2,6-di(trifluoromethyl)phenyl, tert-butyl, cyclohexyl or pentafluorophenyl.
Preferably L is a halide or a moiety of the formula xe2x80x94Z3xe2x80x94R11, C1-C10 alkyl, fluorinated C1-C10 alkyl, C4-C20 aryl or fluorinated C4-C20 alkyl; more preferably L is F, pentafluorophenyl, or a moiety of the formula xe2x80x94Z3xe2x80x94R11.
Preferably d is an integer from 0 to 6, more preferably an integer from 0 to 4, and most preferably d is 0 or 2.
Preferably e is an integer from 1 to 4, more preferably an integer from 1 to 2 and most preferably e is 2.
Preferably, the sum of d and e is an integer from 1 to 6, more preferably 2 to 4.
Preferably R11 is fluorinated C1-C10 alkyl.
Preferably R9 is substituted or unsubstituted P1,P2-substituted arylene or fluorinated arylene, or substituted or unsubstituted P1,P2-substituted cycloalkylene or fluorinated cycloalkylene, such as cyclopentylene, and preferably cyclohexylene. As used in this invention, P1,P2-substituted arylene/cycloalkylene refers to an arylene/cycloalkylene moiety in which xe2x80x94Z1xe2x80x94R8xe2x80x94 and xe2x80x94Z2xe2x80x94R10xe2x80x94 groups are in P1- and P2-positions of the arylene/cycloalkylene moiety, respectively. Thus, for example, 1,2-substituted phenylene refers to a phenylene group having xe2x80x94Z1xe2x80x94R8xe2x80x94 in the 1-position of the phenyl ring and xe2x80x94Z2xe2x80x94R10xe2x80x94 group in the 2-position of the phenyl ring. xe2x80x9cSubstituted or unsubstitutedxe2x80x9d refers to the presence or absence of one or more substituents on the phenyl (or other appropriate) ring moiety, respectively. Such substituents can be F, Cl; Br; I; an alkyl group including cyclic alkyl and alkyl groups containing F, Cl, Br and/or I; and an aryl group including aryl groups containing F, Cl, Br and/or I and heteroaryl groups. For an electrolyte, R9 can also be C1-C4 alkylene or fluorinated C1-C4 alkylene, in particular xe2x80x94C(CF3)2xe2x80x94 moiety.
Preferably x is a bond or 1.
Preferably each of R12 and R13 are independently fluorinated C1-C4 alkyl. More preferably R12 and R13 are independently trifluoromethyl or perfluoroethyl, most preferably R12 and R13 are trifluoromethyl.
Alkyl groups according to the present invention are aliphatic hydrocarbons which can be straight or branched chain groups. Alkyl groups optionally can be substituted with one or more substituents, such as Cl, Br, I, alkenyl, alkynyl, aryl, hydroxy, alkoxy, carboxy, oxo or cycloalkyl. There may be optionally inserted along the alkyl group one or more oxygen, sulfur or substituted or unsubstituted nitrogen atoms. Exemplary alkyl groups include methyl, ethyl, i-propyl, n-butyl, t-butyl, chloromethyl, trichloromethyl, and pentafluoroethyl. Alkyl groups containing at least one fluorine is specifically refered herein as fluorinated alkyl groups.
Aryl groups are carbocyclic or heterocyclic aromatic ring moieties. Aryl groups can be substituted with one or more substituents, such as a Cl, Br, I, alkenyl, alkyl, alkynyl, hydroxy, alkoxy or cycloalkyl. Exemplary aryl groups include, phenyl, p-methylphenyl, p-tert-butylphenyl, thienyl, furanyl, pyrimidinyl, pyridyl, oxazolyl, isoxazolyl, and thiophenyl. Aryl groups containing at least one fluorine is specifically refered herein as fluorinated aryl groups.
M1 of the polyfluorinated anion of the present invention may contain a mixture of polyfluorinated alkoxide and non-fluorinated alkoxide ligands.
Specific polyfluoroalkoxide ligands for anion of formula I (i.e., compound of formula III), include, but are not limited to, the following ligands:
a polyfluoroalkoxide ligand where Z is O, R1 is methylene, b and c are 0, a is 4, and R2, R3 and R4 are F; and
polyfluoroalkoxides where Z is O and R1 is a bond, and
R2 is trifluoromethyl, and each of R3 and R4 is independently phenyl or methyl;
R2, R3 and R4 are trifluoromethyl;
R2 is trifluoromethyl, R3 is phenyl, and R4 is phenyl or pentafluorophenyl; and
R2 and R3 are phenyl, and R4 is pentafluorophenyl.
Specific polyfluoroalkoxide ligands for anion of formula II (i.e., compound of formula IV), include, but are not limited to, the following ligands:
n is 1 and the xe2x80x94Z1xe2x80x94R8xe2x80x94R9xe2x80x94R10xe2x80x94Z2xe2x80x94 moiety comprises: 
xe2x80x83where each of R14, R15, R16, and R17 is independently H, C1-C10 alkyl, fluorinated C1-C10 alkyl, C4-C20 aryl, or fluorinated C4-C20 aryl. Preferably, R14 and R17 are trifluoromethyl, R15 is H, and R16 is phenyl.
Unlike other anions containing chelating dialkoxide groups, compounds II and IV of the present invention have improved stability (thermal, hydrolytic and electrochemical) lower toxicity, and/or higher synthetic yields. Moreover, compounds of the present invention, in particular lithium salts, have high conductivity making them particularly useful as electrolytes in electrochemical devices.
A variety of counter-cation species, including metal cations such as Li, K, Na, Mg, Ca, and Cs; trityl cation; pyridinium cations such as 2,6-pyridinium cation; and 2,6-lutidinium cation, can be prepared from the anions of the present invention. For example, by cation-exchange reaction, the trityl (CPh3+) salt can be prepared by metathesis of Li salt of the anions with CPh3Cl in 1,2-dichloroethane.
Without being bound by any theory, it is believed that the high conductivity of lithium salts of the compounds of the present invention is due to Li+ ion being weakly bonded to several alkoxide oxygen atoms and possibly being bonded to several CF3-group fluorine atoms, similar to Tl+ ions in Tl2Zr(HFIP)6. In contrast, the Li+ ion in the unfluorinated salt LiNb(OEt)6 is believed to be strongly bonded to only four ethoxide oxygen atoms from two adjacent Nb(OEt)6xe2x88x92 anions forming a pseudo-tetrahedral LiO4 core.
Compounds containing the polyfluorinated anion of the present invention have high electrical conductivity making them particularly useful as electrolytes for electrochemical devices. Exemplary electrochemical devices include batteries, such as lithium batteries or lithium ion batteries for a variety of applications; other type of batteries; fuel cells; electrical double layer capacitors; sensors; and electrochromic displays. Such electrochemical devices can be used in a variety of applications including electrochemical devices for electric vehicles, lap top computers, and other applications requiring an energy source. As table 1 shows, lithium salts of the polyfluorinated anions of the present invention have high electrical conductivities in organic solvents. Specifically, the compounds of the present invention have high electrical conductivity in DME compared to other fluorine-containing lithium salts such as LiOTf.
Particularly useful lithium salts of the compounds of the present invention in batteries include LiB(HFPOP)2, LiB (HFAPOP)2, and LiB (HFTPOP)2.
Again referring to Table 1, the lithium salts of the polyfluorinated anions of the present invention are at least about two orders of magnitude higher in electrical conductivity than lithium triflate. Thus, the amount of a compound of the present invention required in an electrochemical device to achieve a similar electrical conductivity in an organic solvent such DME is about 1% of the amount of other fluorine-containing electrolytes such as LiCF3SO3.
A lithium salt of the polyfluorinated anion of the present invention has an electrical conductivity of at least about 4 xcexcScmxe2x88x921 in DME at about 0.01 M concentration at about 25xc2x0 C., preferably at least about 60 xcexcScmxe2x88x921, more preferably at least about 150 xcexcScmxe2x88x921, and most preferably at least about 180 xcexcScmxe2x88x921.
Without being bound by any theory, it is believed that the weak bonds between the Lixe2x88x92 cation and the CF3 groups are responsible for the high electrical conductivity in low dielectric solvents. Indeed, it is believed that the high degree or fluorination and the weak coordination between the Li+ cations in the C-F bonds differentiate the lithium salts of the present invention from other fluorine-containing lithium salts.
The electrochemical stability of a representative compound is shown in Table 2 below. Specifically, Table 2 lists anodic stability of a compound containing a chelating group HFTPOP, e.g., a bidentate group. The anodic stability shows the relative stability of the compound and the potential for oxidation of an anode containing the compound relative to lithium.
The polyfluorinated anions of the present invention can also be used in a variety of organic reaction catalysts where a weakly coordinating anion improves the yield, selectivity and/or the rate of catalytic reaction by the corresponding cation including in catalysts for conjugate additions and Diels-Alder reactions. The compounds of the present invention comprise a weakly coordinating anion, i.e., polyfluorinated anion, which enhances the catalytic activity of the associated metal cation. Exemplary catalytic reactions that have recently received a considerable attention are lithium-catalyzed Diels-Alder reactions and lithium-catalyzed 1,4-conjugate addition reactions. As shown below, using LiNb(HFIP)6, 1, as a catalyst in 1,4-conjugate addition reaction of silyl ketene acetal 2 to the sterically encumbered xcex1,xcex2-unsaturated carbonyl compound 3 gave the 1,4-addition product 4 in 93% yield. 
Reaction conditions: 1,2-dichloroethane (DCE) solvent, 0.1 M of 3, 0.2 M of 2, 0.01 M of LiNb(HFIP)6 and 0.01 M of hexamethylphosphoramide (HMPA) at 24xc2x0 C. for 30 hours.
Formation of only the 1,4-addition product 4 was observed under these conditions. Interestingly, when HMPA was left out of the reaction mixture, a mixture of 4 and the 1,2-addition product 5 was observed after only 10 minutes (95% isolated yield, 4:5 mole ratio=1:5). Without being bound by any theory, it is believed that Li+ ion coordinates with HMPA to produce a sterically more hindered enone-lithium ion complex, thus favoring addition of the ketene at a site more distant from the carbonyl carbon, i.e., 1,4-addition, over addition of the ketene to the carbonyl carbon, i.e., 1,2-addition reaction. Because lithium compounds of the present invention are similar to lithium compounds disclosed in PCT Patent Application No. PCT/US98/19268 and U.S. patent application Ser. No. 09/151,852, lithium compounds of the present invention are expected to provide a similar reaction selectivity.
A comparison of the ability of LiNb(HFIP)6 and two other lithium catalysts to increase the formation of 1,4-conjugate addition product is shown in Table 3. The weaker Lewis acidity of the Li(HMPA)+ complex results in a decreased reaction rate, which is evidenced by the longer reaction time required when HMPA is added to the reaction mixture. The results obtained with LiNb(HFIP)6 are comparable to the results obtained with the very active catalyst LiCo(C2B9H11)2. Product yields were substantially lower when LiClO4 was the catalyst. Furthermore, when LiClO4 was employed in the presence of co-catalyst HMPA, the ratio of 4:5 improved only to 1.3:1. Without being bound by any theory, it is believed that the larger size and/or more weakly coordinating ability of Nb(HFIP)6xe2x88x92 to Li+ compared with ClO4xe2x88x92 is responsible for the difference in catalytic activity between LiClO4 and LiNb(HFIP)6.
The polyfluorinated anions of the present invention that are sterically bulkier, i.e., larger, than Nb(HFIP)6xe2x88x92 afford lithium-ion catalysts that are more regioselective and/or more active in the absence of HMPA. Moreover, enantiomerically enriched polyfluorinated anions of the present invention containing a polyfluorinated alkoxide having a chiral center afford lithium-ion catalysts that are enantioselective, i.e., produce an enantiomerically enriched product. A chiral center of a carbon atom, of course, is a carbon atom to which four different groups are attached; however, the ultimate criterion of chirality of a compound is nonsuperimposability on the mirror image. Facially selective, enantioselective or stereoselective synthetic reactions are those in which one of a set of stereoisomers is formed predominantly or exclusively. Preferably, one isomer is produced in at least about 50 percent enantiomeric excess. Enantiomeric excess is the amount of difference between one enantiomer and the other enantiomer in the product composition. Enantiomeric excess can be expressed by the following formula: %ee=(Rxe2x88x92S)/(R+S), where R is amount of one enantiomer and S is the amount of the other enantiomer, for example, %ee of a product composition containing 98% of one enantiomer and 2% of the other enantiomer is 96%. More preferably, one isomer is produced in at least about 80 percent enantiomeric excess, still more preferably at least about 90 percent enantiomeric excess, even more preferably at least about 95 percent enantiomeric excess, and most preferably at least about 98 percent excess over the other enantiomer.
Lithium salts of the polyfluorinated anions of the present invention can be combined or mixed with a polymer to prepare polymeric materials that exhibit lithium ion conductivity. Such materials, referred to as salt-in-polymer solid electrolytes or solid polymer electrolytes, can be used as electrolytes for solvent-free high-energy-density lithium-based batteries. A polymer can also include a linker which allows a direct linkage of the compound of the present invention to the polymeric structure by a chemical bond formation between the polymer and the compound of the present invention. The polymers useful for the present invention have a rubbery physical characteristic. Generally, suitable polymers have one or more of the following identifying characteristics: 1) ability to dissolve lithium salts of weakly coordinating anions and/or to coordinate, albeit weakly, to the lithium cations of lithium salts of weakly coordinating anions; 2) ability to maintain low glass-transition temperatures with varying amounts of lithium salts dissolved therein; and 3) the ability to possess high electrical conductivities, especially high lithium-ion conductivities, i.e., higher than lithium triflate/polymer mixture at a given temperature). Exemplary polymers useful for the present invention include polyethylene glycol; polyethylene; polypropylene; polystyrene; polybutadiene; poly(vinyl fluoride); polychloroprene; poly(alkyl siloxane) such as poly(dimethylsiloxane); poly(vinyl chloride); poly(ethylene imine); and poly(alkylene oxide) such as poly(propylene oxide), amorphous poly(ethylene oxide) and poly(ethylene oxide). Preferably the polymer is selected from the group consisting of amorphous polyethylene oxide (aPEO), poly(alkylene oxide), poly(alkyl siloxane), poly(vinyl fluoride), poly(vinyl chloride), polychloroprene, polybutadiene, polyethylene and poly propylene; more preferably from the group consisting of aPEO, poly(vinyl fluoride), poly(vinyl chloride), polychloroprene, polybutadiene, polyethylene and polypropylene; and most preferably from the group consisting of aPEO, polybutadiene, polyethylene and polypropylene.
The present invention also includes salt-in-polymer electrolytes having alkali metal salts containing the polyfluorinated anions of the present invention. Compounds containing these polyfluorinated anions have superior glass transition temperatures, impedance measurements and cation transference numbers than compounds containing other anions.
The polyfluorinated anions of the present invention can also be used as co-catalysts for activating transition-metal-catalyzed olefin polymerization and as counterions for polymerization photoinitiators.